<5^47070W Lund University • Sweden Lund Institute of Technology Department of Building Science Report TABK--96/1008 LuTAT)L-l'Ae<--/008' Controlling Indoor Climate ; ->•: >-r ^1 & Uk % <f ■m Passive cooling of residential buildings m hot-humid climates in China ojsrRjBunoN of this mckmmmmMttw Zhiwu Wang Building Science Lund University Lund University, with eight faculties and a number of research cen ­ tres and specialized institutes, is the largest establishment for re­ search and higher education in Scandinavia. The main part of the University is situated in the small city of Lund which has about 94 000 inhabitants. A number of departments for research and edu ­ cation are, however, located in Malmo. Lund University was founded in 1666 and has today a total staff of 6 000 employees and 37 000 students attending 60 degree programmes and 850 subject courses offered by 170 departments. Department of Building Science The Department of Buildning Science is part of the School of Archi­ tecture within the Faculty of Technology. The Department has two professorial chairs, Building Science and Building Services. Research at the Department is concentrated on energy management, climatic control and moisture problems. The main areas of research are: • design and preformance of new low-energy buildings • energy conservation in existing buildings • utilization of solar heat • climatic control • climatic control in foreign climates • moisture research DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. Organization Document name LUND UNIVERSITY DOCTORAL DISSERTATION Department of Building Science Date of issue October 23,1996 P.O. Box 118 S-221 00 Lund coden : LUTADL/TABK-1008-SE Sweden Authorfs) Sponsoring organization Zhiwu Wang The Swedish Council for Building Research Title and subtitle Controlling Indoor Climate. Passive cooling of residential buildings in hot-humid climates in China Abstract Overheating is a paramount problem in residential buildings in hot and humid climates in China during summer. This study aims to deal with the overheating problem and the problem of poor air quality in dwellings. The main objective is to improve indoor thermal conditions by passive cooling approaches, climatisation techniques in buildings without auxiliary cooling from air conditioning equipment. A field study is carried out in southern China, in order to ascertain the current situation of indoor environment in residen­ tial buildings. By literature survey, a thermal comfort index SET (Standard Effective Temperature) is selected as a suitable index to evaluate indoor thermal environment in a hot humid climate. This thesis focuses on the study of cross-ventilation in apartments, which is one of the most effective ways of natural cooling in a hot humid climate, but is also one of the least understood parts in controlling indoor climate. The Computa ­ tional Fluid Dynamics (CFD) technique is used, which is a new approach, since cross-ventilation studies have been con­ ventionally made by wind tunnel tests. The validations of the CFD technique are examined by a comparison between wind tunnel tests and computer simulations. The factors influencing indoor air movement are investigated for a single room. Cross-ventilation in two apartments is studied, and the air change efficiency in a Chinese kitchen is calculated with CFD techniques. The thermal performance of ventilated roofs, a simple and widely used type of roof in the region, is specially addressed by means of a full-scale measurement, wind tunnel tests and computer simulations. The full-scale measurement compares thermal performance of ventilated roofs with other types of roofs. The wind tunnel tests examines ventilation behavior of the roofs, and computer simulations study the parameters influencing the thermal properties of ventilated roofs. An inte­ grated study of passive cooling approaches and factors affecting indoor thermal comfort is carried out through a case study in a southern Chinese city, Guangzhou. This thesis demonstrates that passive cooling measures have a high potential in significantly improving indoor thermal conditions during summer. This study also gives discussions and conclusions on the evaluation of indoor thermal environ­ ment; effects influencing cross-ventilation in apartments; design guidelines for ventilated roofs and an integrated study of passive cooling. Indoor climate, Passive cooling, Residential buildings, Roofs, Cross-ventilation, Computational Fluid Dynamics (CFD), Thermal comfort, Environment, Hot humid climate, China. Classification system and/or index terms (if any) Supplementary bibliographical information Language English ISBN ISSN and key title 1103-4467 Rapport TABK Recipient ’s notes Number of pages 254 Price Security classification Distribution by (name and address) Lund University, Lund Institute of Technology, Department of Building Science, P.O. Box 118, S-221 00 Lund, Sweden I, the undersigned, being the copyright owner of abstract of the above-mentioned dissertation, hereby grant to all reference sources permission to publish and disseminate the abstract of the above-mentioned dissertation. mi Signature Controlling Indoor Climate Passive cooling of residential buildings in hot-humid climate in China av Zhiwu Wang Civilingenjor och Tekn Lie Akademisk avhandling som for avlaggande av teknologie doktorsexamen, vid tekniska fakulteten vid Lunds universitet kommer art offendigen forsvaras i sal B, vid sektionen for arkitektur, Solvegatan 24, Lund, onsdag den 23 oktober, 1996 kl 09.15. Controlling Indoor Climate Passive cooling of residential buildings in hot-humid climates in China Zhiwu Wang This report relates to Research Grant No 890947-8 from the Swedish Council for Building Research to the Department of Building Science, Lund University, Institute of Technology, Lund, Sweden. Controlling Indoor Climate Keywords Indoor climate, Passive cooling, Residential buildings, Roofs, Cross­ ventilation, Computational Fluid Dynamics (CFD), Thermal com­ fort, Environment, Hot humid climate, China. © copyright Zhiwu Wang and Department of Building Science, Lund University, Institute of Technology, Lund 1996 The English language corrected by L J Gruber BSc(Eng) MICE MIStructE Layout: Hans Follin.LTH, Lund Cover: Air movement in an apartment Printed by KFS AB, Lund, Sweden, 1996 Report TABK—96/1008 Controlling Indoor Climate. Passive cooling of residential buildings in hot-humid climates in China. Lund University,Lund Institute of Technology, Department of Building Science, Lund, Sweden ISSN 1103-4467 ISRN LUTADIVTABK-1008-SE Lund University, Lund Institute of Technology Department of Building Science P.O. Box 118 Telephone: +46 46 222 73 47 S-22100 LUND Telefax: +46 46 222 47 19 Sweden E-mail: [email protected] 2 Abstract Abstract In the hot and humid climates of China, overheating is a paramount problem in residential buildings during summer. Although air con­ ditioning can solve the problem, this consumes a large amount elec­ tricity and also causes environmental problems. This study aims to deal with the overheating problem and the problem of poor air qual­ ity in dwellings. The main objective is to improve indoor thermal conditions by passive cooling approaches, climatisation techniques in buildings without auxiliary cooling from air conditioning equip­ ment. A field study is carried out in southern China, in order to ascer­ tain the current situation of indoor environment in residential build ­ ings. By literature survey a thermal comfort index SET (Standard Effective Temperature) is selected as a suitable index to evaluate indoor thermal environment in a hot humid climate. This thesis focuses on the study of cross-ventilation in apartments, which is one of the most effective ways of natural cooling in a hot humid climate, but is also one of the least understood parts in con­ trolling indoor climate. The Computational Fluid Dynamics (CFD) technique is used, which is a new approach, since cross-ventilation studies have been conventionally made by wind tunnel tests. The validations of the CFD technique are examined by a comparison between wind tunnel tests and computer simulations. The factors influencing indoor air movement are investigated for a single room. Cross-ventilation in two apartments is studied, and the air change efficiency in a Chinese kitchen is calculated with CFD techniques. The thermal performance of ventilated roofs, a simple and widely used type of roof in the region, is specially addressed by means of a full-scale measurement, wind tunnel tests and computer simulations. The full-scale measurement compares thermal performance of ven- 3 Controlling Indoor Climate tilated roofs with other types of roofs. The wind tunnel tests exam­ ines ventilation behaviour of the roofs, and computer simulations study the parameters influencing the thermal properties of venti ­ lated roofs. An integrated study of passive cooling approaches and factors affecting indoor thermal comfort is carried out through a case study in a southern Chinese city Guangzhou. This thesis demonstrates that passive cooling measures have a high potential in significantly improving indoor thermal conditions during summer. This study gives discussions and conclusions on the evaluation of indoor thermal environment; effects influencing cross­ ventilation in apartments; design guidelines for ventilated roofs and an integrated study of passive cooling. Finally the study calls for greater